The primary aim of the Animal Core B is to continue to provide SAMP1/YitFc (SAMP) mice for use in each of the individual projects comprising the Program Project. The Animal Core will maintain the SAMP breeding colony, its derivations including SAMP congenic lines, as well as the parental control (AKR) colony in a common centralized facility under uniform environmental conditions. Housing of the aforementioned mice is critical to the success of the program, particularly in the light of evidence that environmental factors, such as colonization of specific commensal bacteria, can affect the presence or course of disease. Centralization of animal production also reduces costs, by eliminating redundant breeding colonies, and ultimately reduces the overall number of animals required for experimentation by ensuring efficient utilization of experimental mice by each of the five projects. In addition, coordination of the distribution of experimental mice by the Animal Core allows optimal communication and collaboration between each of the five projects. A second specific aim is to continue to provide investigators with centralized histological analyses of intestinal inflammation and other morphological parameters in SAMP mice, to monitor phenotypic and histopathological changes over time. A major strength of this component of the Animal Core is the continued availability of an experienced Gl pathologist (CA Moskaluk) to perform periodic histological analyses of SAMP tissues and to provide ongoing consultative services to PPG investigators regarding the pathological features of disease in this model. The third specific aim is to continue to serve as a resource for providing mice with specifically introduced genetic mutations onto the SAMP background strain that will be useful to multiple projects within the program. This component of the Animal Core interacts closely with the Mouse Genetics Core Facility at UVA, directed by Dr. Marcia McDuffie (Principal Investigator of Project 2). Using speed congenic technology, transfer of these induced mutations into the appropriate background can be accomplished in three to four generations. Dr. Theresa Pizarro will continue to direct the overall activities of the Program Project Animal Core, and a committee consisting of the Core Director, Core Consultant (CA Moskaluk), and the PI of the Program Project (F Cominelli), will meet on a regular basis to address routine quality control and prioritization issues. In addition, an oversight committee consisting of members of the Advisory Board will review the overall operation of the Core on a yearly basis.